Generally, in a receiving system, a SAW filter is used to eliminate interference that causes in-band noise and is produced by aliasing and system saturation by the use of an out-of-band high-level signal.
An exemplary SAW filter is a surface acoustic wave filter. It is also referred to as a communication filter that uses physical vibration of a piezoelectric substrate. The SAW may filter act as a band-pass filter that allows only the frequencies that are the same as the physical frequencies of the SAW filter to pass through. Such a SAW filter may have even narrower bandwidth for signals to pass through, compared to typical filters using the general LC resonance principle. Hence, the SAW filter may be used to precisely pick up a desired signal within a narrow bandwidth by filtering signals of unnecessary frequencies.
However, typical SAW filter is physically configured and thus there is a limit in reducing its size. In addition, while a receiver may be desired to be integrated with the SAW filter into a single chip, the SAW filter may not be mounted on the same chip. Instead, it is normally placed outside of the receipt chip. Moreover, the SAW filter is relatively expensive, thus increasing the manufacturing cost of the receiver. Therefore, while a SAW filter may be desired for a mobile communication terminal, one may be faced with increased cost of the resulting receiver and difficulty of implementing a one-chip receiver.